|Van Genuchten, Martinus|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/14/1995
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: We used a highly instrumented tile-drained farm in central New Mexico to quantify water and chemical transport to shallow groundwater. A rapid response in tile drain chemistry was seen following rainfall or irrigation. Chemicals present in high concentrations near the soil surface appeared in the drain water within hours. Thus, after a nitrogen fertilization and for a period of several months, nitrate peaks arrived in the drainage shortly after an irrigation. Once nitrate was depleted in the upper 30 cm of soil, nitrate peaks no longer appeared in the drainage. Chloride, which was concentrated near the soil surface due to evapotranspiration and capillary rise, similarly arrived rapidly in drainage following an irrigation. Results from a surface application of chlorpyrifos and a separate application of bromide tracer will also be presented. The data support a model of rapid flow of surface-applied water rto groundwater via preferential pathways, followed by slower recharge due to the flow of matrix water.